How to rewind the windings of the coils of electrical devices to a different type of current

When repairing electrical equipment (relays, starters, etc.) When rewinding coil windings from direct current to alternating current and vice versa, it is more convenient to use simple formulas rather than to produce them magnetic circuit calculation.

Let's say you want to rewind the coil coils from permanent to alternating current… Before scrolling, you must:

1) measure the ohmic resistance (R1 or R2), ohm;

2) measure the impedance of the winding (Z1 or Z2 by the ammeter and voltmeter method at alternating current Ohm;

3) count the number of turns w1 or w2

4) determine the diameter of the wire d1 or d2, mm.

R values1, Z1, w1, d1 Recommend to constant current circuit, i.e. before rewinding and respectively R2, Z2, w2, d2 — to the AC circuit, i.e. after rewinding.

When rewinding the winding, equality of ampere turns is required, i.e.

Since in alternating current the inductive resistance is large, the number of turns coils must be reduced n times: w2 = w1 / n

To maintain the ampere turns, the coil current must increase by n times, so the wire cross-section must also increase by n times:

Impedance of a new coil after reducing the number of turns

Substituting the values ​​of w2 and Z2 into an expression and transforming it, we find n

where Z1 — total resistance of the winding before rewinding, Ohm.